A. This has been tried using heat, acids, skin peelings, and it works to a degree, says Netherlands fingerprints expert Hans van den Nieuwendijk. The police would not be able to identify the original fingerprints. But if the person is arrested again and re-fingerprinted, the new prints would be so special they would be even easier to track. BTW, passing blame off on one's identical twin won't work because even twins' prints are unique.

Q.If extraterrestrial aliens searched the heavens looking for beings like us, could they find us? Wouldn't it be like locating a needle in a haystack? ­ C. Sagan

A. Imagine a civilization somewhere in our Milky Way galaxy being told to look in the direction of our Sun out of the 400 billion or so stars in the galaxy, to try to pick up signs of intelligent life, poses Case Western Reserve University's Lawrence Krauss in The Physics of Star Trek.

Knowing where to look would be quite a clue. Would it be enough? Life has existed on Earth for much of its 4.5 billion year history, but only in the last 50 years have humans been transmitting telltale signals into space, and only in the last 25 years have our radio telescopes beamed out sufficiently powerful signals to signal our presence.

"Assuming an alien civilization chose to make its observation at some random time during Earth's history, the possibility of discovering us would be about one in 100 million. And that's if they knew exactly where to look!"

Our own searches face similar obstacles. So far, our radio probes have scrutinized fewer than a thousand stellar habitats, says Seth Shostak of the SETI Institute (Search for Extraterrestrial Intelligence). Larger sweeps of the sky may lack sufficient sensitivity to pick up signals.

It's also possible we're not listening at the right frequencies or at the right time. "But the real bottom line is that SETI is still a small effort, privately funded, with a staff numbering less than the crew of a large fast-food restaurant. It's way too early to say the needle isn't out there in the haystack somewhere waiting to be found," Shostak says.

Q.There are 8 million tons of gold out there, totally unguarded, available for the taking. But nobody's taking it. Why not? ­B. Cassidy

A. It's dissolved in the world's oceans, along with five billion tons of uranium, says Isaac Asimov in On Numbers. But it's generally not economically feasible to mine the stuff, so there it stays, about one five-millionth ounce of gold per ton of water, one ten-thousandth ounce of uranium.

Ocean water is overall about 3.5 percent solids, mostly salt. If this were removed and spread evenly over the 50 U.S. states, the salt top would be 1.5 miles thick. If the oceans were a cocktail in a tumbler as big around as a medium city (1300 sq. miles), the glass would have to stand as high as the Moon to hold all the water.

Q.Do humans have white and dark meat like a chicken? ­Col. H. Sanders

A. A chicken's white breast muscles provide quick power for flight but tire quickly, says Ohio State University physiologist Jon Linderman. The dark leg muscles are for endurance, enabling it to walk for hours. This is reversed in ducks or geese that must migrate long distances. Fish have red, pink, and white muscles– designed for slow, intermediate or fast action.

Any well-fed cannibal can tell you humans too have white and dark meat, though not as pronounced as fish or fowl and varying with the specimen. In a white meat mood? Look for a sprinter or power lifter, with predominantly pale fast-twitch muscle fibers. Redder meat– more capillary-rich and adept at oxygenation shows up in red slow-twitch- fibered endurance athletes such as cyclists, marathoners.

Showing how specialized this gets, adds James Kalat in "Biological Psychology," Swedish ultramarathoner Bertil Jarlaker once ran 2,188 miles in 50 days on slow-fibered legs, with minimal fatigue, but his underdeveloped fast fibers cut his short-race speed to a mediocre 9 minutes per mile.

Q.It's pumped out at more than a gallon a minute, 80 gallons per hour, 1900 gallons a day, 700,000 gallons a year– at a flow speed up to about one mph. When all is said and done, some 50 million gallons have been pumped, enough to fill a million bathtubs, or 50 10-ft.-deep swimming pools the size of football fields. Identify this vital lifestuff. ­B. Stoker

A. Blood flowing out of a single human heart, impressive not for its speed of circulation but the workhorse tenacity of the pump, enabling a lifetime of heart-felt living, says University of Wisconsin-Madison physiologist James Ervasti.